The present invention relates to a microwave oscillator.
Microwave oscillators are devices used for generating waveforms whose frequency range lies between a few hundred and several tens of thousands of megahertz. Typically, microwaves are electromagnetic waves which have a wavelength in the centimeter range. Microwaves occupy a region in the electromagnetic spectrum which is bounded by radio waves on the side of the longer wave lengths and by infrared waves on the side of the shorter wavelengths.
Microwave oscillator techniques, of course, are well known in the art. In particular, microwave oscillators with dielectric resonators are known which operate in a TE01.delta. mode. Prior art microwave oscillators which utilize the dielectric resonators in the TE01.delta. mode have a weak electric field at the center of the resonator. Consequently, the tuning of the TE01.delta. resonator by a dielectric rod at its center is ineffective. For this reason, conventional oscillators with the dielectric resonators are often tuned by means of a metal tuning rod or metal plate. A side effect of introducing the metal object in the vicinity of the dielectric resonator is an appreciable lowering of the Q factor.
Typically, the TE01.delta. mode is conventionally considered as a desired mode while a TM01.delta. mode is considered an undesired mode. The problem with such prior art microwave oscillators is that the tuning range is typically no more than one percent of the operating frequency without degrading temperature stability or Q factor. It would therefore be highly desirable to provide an improved microwave oscillator with dielectric resonator which provides an increased tuning range over that of the prior art.
In view of the above background, it is an objective of the present invention to provide an improved microwave oscillator with dielectric resonator.